Breast cancer survivors could be at risk of further illness – being vigilant is key

Breast cancer is the most common in the UK with around 56,000 people diagnosed each year, almost all of them women. Five-year survival rates have been increasing over time, reaching 87% by 2017 in England.

However, people who survive are at risk of a second cancer. Until now the exact risk has been unclear, but women and men who survive breast cancer are at a 24% and 27% greater risk of tumours elsewhere than the wider population respectively.

A team led by researchers at Cambridge University have analysed data from more than 580,000 female and more than 3,500 male breast cancer survivors diagnosed between 1995 and 2019 using the National Cancer Registration Dataset. First author, Isaac Allen of Cambridge University said: “It’s important for us to understand to what extent having one type of cancer puts you at risk of a second cancer at a different site.

“The female and male breast cancer survivors whose data we studied were at increased risk of a number of second cancers. Knowing this can help inform conversations with their care teams to look out for signs of potential new cancers.” The researchers found double the risk of cancer in the unaffected breast, an 87% greater risk of endometrial cancer, 58% greater risk of myeloid leukaemia and 25% greater risk of ovarian cancer.

Age at diagnosis is important, too – females diagnosed with breast cancer under 50 were 86% more likely to develop a second cancer, whereas women diagnosed after age 50 were at a 17% increased risk. Women from the most socio-economically deprived backgrounds were at 35% greater risk of a second cancer compared to women from the least deprived backgrounds. This may be because smoking, obesity, and alcohol consumption – established risk factors for these cancers – are more common among more deprived groups. The risk of a second cancer in male breast cancer survivors is low.

For example, for every 100 men diagnosed with the disease at age 50 or over, about three developed cancer in the other breast during a 25-year period. Male breast cancer survivors, however, are also 58% more likely than the general male population to develop prostate cancer.

Cancer Research UK’s senior cancer intelligence manager, Katrina Brown, said: “This study shows us that the risk of second primary cancers is higher in people who have had breast cancer – and that this can depend on someone’s socioeconomic background. But more research is needed to understand what is driving this difference and how to tackle these health inequalities.” And being more vigilant.